Sloane Stephens beaten, Melanie Oudin wins in Washington opener

Tennis: This year's Australian Open semifinalist and Wimbledon Quarterfinalist Sloane Stephens of USA slumped to a defeat in the first round of Citi Open WTA Tennis Championship in Washington, USA.

The world no.15, who is American no.2 behind Serena Williams right now, was beaten in straight sets by Olga Puchkova of Russia in straight sets 7-5, 6-3. 25-year-old Puchkova is 73 ranks lower than 20-year-old Stephens in the rankings.

Another American youngster Melanie Oudin won her match as she came over Australia's Anastasia Rodionova in straight sets 7-5, 6-3. The 21-year-old Oudin had made headlines when she reached Quarterfinals of US Open at the age of 17, four years ago. She is now ranked 141 in the world.

In another match of the day, Andrea Petkovic of Germany defeated American qualifier Jessica Pegula in straight sets 6-2, 7-5 to move into the second round. Andrea Petkovic is a former top 10 player and her highest ranking is world no.9.